Style Rules with a maximum line length

[jalextowle]

Description

The code formatter (now in PR #17) does not take line lengths into consideration. A good formatter will have different style options for different line lengths.

Acceptance Criteria

A backtracking formatter that tries to use a single-line style but switches to a multi-line style if the maximum line length has been hit.

Bonus

The maximum line length is a configurable variable.